Update for slnx format

Author: ghogen

docs/msbuild/customize-solution-build.md

@@ -35,6 +35,9 @@ When you have many solution files that you want to extend in the same way, but y
 
 When you have *Directory.Solution.props* or *Directory.Solution.targets* in a root folder, but you have a solution under that folder that you don't want to import them, you can use the solution-specific files mentioned previously `before.{solutionname}.sln.targets` and `after.{solutionname}.sln.targets` to set the properties `$(ImportDirectorySolutionProps)` and `$(ImportDirectorySolutionTargets)` to false. Or, you can use the properties `$(DirectorySolutionPropsPath)` and `$(DirectorySolutionTargetsPath)` to specify a different location for those files. This could be helpful if you have various subsets of your solutions that require certain property values or targets common to the subsets.
 
+> [!NOTE]
+> The solution build is supported with the `.slnx` solution file format in MSBuild 17.12 and later. Both `before.{solutionname}.slnx.targets` and `before.{solutionname}.sln.targets` work (and likewise for the `after` forms) with MSBuild 17.14 and later.
+
 ## Related content
 
 - [Customize your build](customize-your-build.md).

docs/msbuild/solution-filters.md

@@ -48,6 +48,9 @@ The solution filter doesn't have to be in the same folder as the solution. The p
 
 The backslashes in paths must be doubled, since they're escaped.
 
+> [!NOTE]
+> In the case where you're using the `.slnx` solution file format, supported in MSBuild 17.12 and later, the `.slnx` file takes priority over the `.slnf` file.
+
 ## Example
 
 Here's an example of a filtered solution in Visual Studio:

docs/msbuild/whats-new-msbuild-17-0.md

@@ -55,6 +55,7 @@ In MSBuild 17.8 and later, try the new Terminal Logger (`-terminalLogger` or `-t
 ## Other behavior changes
 
 - `MSBuildCopyContentTransitively` is now on by default, ensuring consistency in output folders on incremental builds.
+- In MSBuild 17.12 and later, MSBuild can build solution files in the `.slnx` format. See [MSBuild command-line reference](./msbuild-command-line-reference.md).
 
 For more changes in this version, see the detailed release notes and for changes in MSBuild versions that you can opt out of, see [change waves](change-waves.md).